Restoring marine coastal ecosystems

Counting the costs and assessing the feasibility

KEY MESSAGES

We examined the cost and feasibility of restoration in marine coastal ecosystems

The median price was around US$80,000 per hectare, the average price was up at US$1,600,000 per hectare

Feasibility ranged from 38% for seagrass, to 65% for coral reefs and saltmarshes

Coasts are popular areas for tourism, recreation, transportation, and development. Unfortunately, our love affair with coastal regions has resulted in significant damage to large areas of natural habitat. The result has been extensive and rapid rates of decline in a range of important ecosystems including seagrass, coral reefs, mangroves, saltmarsh and oysters. And this decline is being witnessed worldwide. Along with the loss of habitat comes a decline of the services they provide (ecosystem services). These include the provision of habitat for threatened, iconic, or fished species; shoreline protection from waves and storm surges; water filtration; and carbon storage to help mitigate climate change.

There is now considerable interest in reversing trends in the decline of coastal ecosystems. This means restoration – the process of removing the factors which are causing ecosystems to disappear, and/or establishing plants or animals to replace those which have been lost. Restoration is also an important element of biodiversity-offsetting projects – where losses of biodiversity from a development at one site are ‘offset’ (replaced) by restoration at another (degraded) site (see Decision Point #63).

A coral nursery in the Florida Keys. Restoration efforts can get incredibly expensive and even then they can be quite risky. (Photo XL Catlin Seaview Survey)

There is one important catch – for restoration to achieve a particular goal, we must be able to anticipate how likely the project is to succeed, and how much it will cost.

Our study examined the cost and feasibility of restoration in marine coastal ecosystems, including seagrass, corals, mangroves, saltmarsh, and oyster reefs. We accomplished this by reviewing the peer-reviewed literature and reports on this topic, and by filling in data gaps by talking to people who do restoration. This was particularly important for oyster reefs, for which data were largely absent from the published literature.

Our review quickly established there is a huge range of costs for different types of marine coastal restoration. The least expensive projects, conducted by volunteers in ‘inexpensive’ developing countries, could be accomplished for less than $2,000 per hectare (all dollar values are in US dollars). But these were more the exception than the rule.

The median (middle) price for coastal restoration was typically around $80,000 per hectare. The average price, however, was up at $1,600,000 per hectare. The big difference between the median and average cost is due to some marine restoration projects being incredibly expensive, costing many millions of dollars per hectare. Examples of these types of projects involve the use of artificial structures to rebuild the ecosystems in ‘expensive’ countries like the USA and Australia.

As an aside, we observed that investment in restoration can be up to 30-times more cost-effective in developing countries than in developed countries. Yet many projects in developing nations go undocumented due to a lower incentive to publish and report on restoration outcomes.

An oyster restoration project. The review revealed that the published literature didn’t have much data on oyster restoration projects such as this. (Photo by Erika Nortemann, The Nature Conservancy)

Information on the ‘feasibility’ of a restoration project succeeding (ie, how likely a project will meet the project objectives) was largely unavailable. Failed projects are often not reported. Instead, for project feasibility we only documented a success indicator in terms of the percentage of restored organisms which survived over the reporting period. Project duration was typically one year or less. Only in a few instances were restoration projects monitored for more than a decade. Feasibility ranged from 38% for seagrass, to 65% percent for coral reefs and saltmarshes.

We were surprised to find that project success was unrelated to the amount of money spent. And restoration cost-per-unit effort did not decrease with increasing project areas (so there was no economies of scale). This suggests that marine restoration techniques still need a bit of work. Further studies will be required to achieve a transition from small-scale to large-scale restoration of marine coastal ecosystems. (It should be noted that this inability to scale up restoration is also an issue on land, see Decision Point #68).

Restoration may be a critical tool used to secure a sustainable future in marine coastal ecosystems. If that’s the case, a lot more effort needs to go into understanding how we can do it more effectively.